The Anti-Monitor is in search of Universes to add to his empire, he then stumbles across the marvel Multiverse and decides to unleash a full scale attack into the Main Marvel 616 universe.
He finds the Phoenix force near the Center of the Universe and decides that it poses too much of a threat to his Plans and decides to Attempt to absorb this entity unto himself. The Phoenix force takes non too kindly to this and resists. and the Titans clash.
Rules: This is anti-monitor at his peak, with the power of one hundred Sinestro, Red Lantern, and Black Lantern Corps rings each combined with his COIE powers. This is the Phoenix force, before it needed a host. The Anti-Monitor's army consists of the "evil" lanterns and the anti-matter superuniverse, but they are mainly there for show. The higher ranked cosmic gods are caught off guard and are unable to interfere.